Piazza San Marco
Historic landmarks come a dime a dozen in Venice, but Torre dell'Orologio (clock tower) is a bit more legendary than most. Centrally located at the entrance to one of the city's oldest marketplaces, the looming structure has stood watch over generations and generations of busy Venetians. By appointment only, visitors can enter the hulking monolith, ascend its stairways, climbing through the complex inner workings of the ancient clock, and taking in some astounding views of the neighborhood below. Check website for exact timings of the tours.